Selfing potential in Epipactis palustris, E-helleborine and E-atrorubens (Orchidaceae)

Factors enabling and limiting self-fertilization were examined in populations of Epipactis palustris, E. helleborine and E. atrorubens located in NE Poland. In these species we found self-compatibility within the same flower (even 100% of fruit set from induced autogamy) and the same inflorescence (reaching 90-100% of fruit set from induced geitonogamy). Facultative autogamy was found only in E. palustris (even 82.5% of fruit set in a bagged inflorescence), due to underdevelopment of the clinandrium and projection of pollinia over the rostellum. Allogamy was predominant in E. helleborine (maximum to 2.8% of fruits set spontaneously) and E. atrorubens (maximum to 3.4%), attributable to a well-developed rostellum and clinandrium and to the position of pollinia. Autonomous selfing takes place during flower wilting, when the viscidium becomes evanescent and the pollinia are fragile. Selfing is enabled mostly by pollinator behaviour, promoting both geitonogamy and autogamy, and influencing mixed-mating.